In accordance with certain embodiments, the present invention relates to methods and apparatus for communicating information through a physical barrier, and, as a specific example, to a non-intrusive annulus pressure monitoring system.
In various situations, it is desirable to transmit information through a physical barrier. For example, in downhole applications, nested tubular members (e.g., casing strings) may extend for thousands of feet below the surface. These casing strings thus cooperate to define annular spaces; and it is often desirable to have information regarding the condition, such as the temperature or pressure, of these annular spaces. As an example, knowledge of a change in condition, such as a change in pressure or temperature, in such an annular space can indicate a loss of sealing integrity between the casing strings or the presence of unfavorable environmental conditions, provoking remedial responses by the operator, for instance.
Unfortunately, traditional annulus monitoring techniques generally require a penetration (i.e., an intrusion) through the wall of one or more of the casing strings to, for example, communicate pressure by means of a hydraulic conduit to pressure monitoring equipment located outside of the annular region or to communicate information obtained by the monitoring equipment disposed in the annular region. For example, conventional techniques often require a port in the casing through which a communication cable from the monitoring equipment in the annular region extends. Similarly, such monitoring equipment may require power from a cable that penetrates the casing string. Penetrations weaken the overall integrity of the given casing string, by providing potential points of leakage and structural weakness.
Therefore, there is a need for improved methods and apparatus for communicating information through a physical barrier. Particularly, there is a need for communicating information through a physical barrier in a non-intrusive manner.